These studies are designed to clarify the mechanisms that may lead to ocular and specifically corneal pathology. Among immunologic mechansims, experimental models to be employed involve a local in vivo graft-versus-host reaction against the corneal endothelium and studies in tissue culture of the action of virus-specific lymphocytes on infected corneal endothelial cells. Studies of corneal wound healing will utilize the polypeptide secretory component of immunoglobulin A as a physiologic marker of conjunctival-corneal epithelial cell metaplasia. The role of secretory component and IgA will also be studied to define the protective role of the secretory immune system in corneal conjunctival infections, utilizing an experimental trachoma in monkeys as a model. Attempts will be made to use corneal endothelial cell tissue cultures to reconstitute the endothelial layer of a cornea in vitro for studies on the transplantation biology of cornea grafts.